Paul,
It shouldn't be too bad to build one from scratch but I have seen some partially built on eBay including some that have been mis-listed as other types of cars. I have not come across any O-scale plans online.
The decals I used came from Tichy Train Group except for the eagle. I got my decal set from eBay. The Tichy set is for the third and later generation cars and comes in U.S. Navy, Department of the Interior, and Atomic Energy Commission. The latter two owned the cars after the U.S. Navy. I adapted the set for my car since it's a second generation car. I made the eagle decal by heavily editing a clear photo I took of the original that was on my car. I then resized it and printed it on decal paper.
